Skype differs from other VoIP-systems by several factors:
Skype is very popular. During the first week in August of 2003, more than 60 thousand people downloaded the Skype-client. Today, Skype is available for the following operating systems: MS Windows, MacOS, IoS, PocketPC, Android and Linux.
Using the software and the Skype network is free, and there is only a nominal price for calls made using «Skype Out» and «SkypeIn» functions, which allow you to make calls from Skype to telephone networks.
Skype is much easier to use than any other VoIP-system. Skype-client is fairly easy to install. In addition to selecting the user name no other configuration is required. And in contrast to SIP-system used by Vonage, Skype-clients can easily work through firewalls and systems of network address translation (NAT).
Skype offers superior sound compressor with quality, which is often superior to the traditional phone system, provided that if the Skype user has a high-speed Internet access.
In addition to voice telephony, Skype supports instant messaging, search and file transfer. Skype uses encryption. Unlike traditional telephony and other VoIP-Systems Skype claims that the transmission of all information is encrypted using 128-bit or higher encryption codes, which they claim makes it virtually impossible to intercept Skype passive dialects, and the ability to decipher and to hear their content.